Blue Ghost
by The-Fourth-Queen
Summary: Where one mischievous turtle in blue meets a mysterious human. Leo's new portal sword isn't the only thing grabbing his attention, and does the arrival of their first human male friend spark new adventures for the turtle team? Raph's maybe a bit overprotective of his blue brother when dealing with all things dark-haired and head-strong. Leo-centric. Casey-centric. HIATUS
1. Mischief Begins

_New Fanfic!_

 _And it's about the New TMNT. More specifically, Leo and Casey (oops, spoilers...)_

 _And even though I know that 2018 Casey Jones would probably be a kid and nothing like what I'm writing- I still like the idea of the 2012 Casey. So let's mix it up- 2018 Turtles with 2012 Casey. Hmm... does this count as crossover?_

 _Hope you enjoy the story!_

* * *

Raph stood a bit taller than he usually did, "I'm telling you Mikey! There's no such thing as ghosts."

Leo scoffed to himself, "Yeah right, just like there's no such thing as mutant turtles!"

Raph sent him a glare, one that Leo shrugged off. The blue turtle continued to lean against the wall, as nonchalantly as he could while his brothers bickered among themselves as to whether floating souls roam the Earth.

Don shook his head, taking on a somewhat supreme air, "The existence of ghosts is…" pausing for dramatic effect, "Very unlikely."

And if Raph would let him, Don would have launched into a lecture as to what the chances of the deceased had of remaining with them. Mikey however, put his foot down and pointed to his brainy brother.

"I'm telling you guys!" he stomped the other foot, "Ghosts are real!"

Don replied just as quickly, "Unlikely,"

Raph folded his arms and nodded to Mikey, "Don's right Mikey." He held up a finger, "Ghosts don't exist."

"DO TOO!" Mikey whipped around to face Leo, "Tell them Leo?"

Leo's eyes widened, "Say what now?"

Mikey put his hands on his hips, "Say how you believe in ghosts!"

Leo's eye ridges shot up, "I do?!"

Mikey nodded passionately, "Yes you do!"

Don rolled his eyes, "Unbelievable,"

Mikey's face fell, those baby eyes going wide with- oh no… the _puppy eyes_ , "Don't you Leo?"

 _Not the puppy eyes._

Leo glanced to his side, as if avoiding direct eye contact would let him stand a chance against those… irresistible… baby… _aww shell._

Leo rubbed the back of his neck, standing straight to look at anything but his brothers, "Of course I do Mikey…"

Raph gasped with all the drama he could muster, and one eye ridge shot up, "Really Leo… You do?"

Even Don was giving him a scrutinizing glare, "Seriously Leo?"

Mikey jumped up with the energy no one should possess, "Yay! Leo's on my side!"

The glee on his face was worth the lie. It was a lie… wasn't it? Leo wasn't sure of himself. But, to deny Mikey right now, even as Don gave them scrutinizing looks and Raph looked ready to break Mikey's heart in two by telling him to knock it off. And… Leo just _couldn't_ deny ghosts right now. Not at the cost of Mikey's weird… worm dance?

Leo's eyes shot open, but he couldn't help his smile, "Woah… Mikey, nice moves there bro!"

Mikey proceeded to wave his arms in the air like some… imitation crab. Leo cracked a grin when Don face-palmed and muttered something about his brothers having no sense of science. And where was Raph?

Leo turned to cast a glance behind him, but no Raph.

"Huh?" Leo practically asked himself, "Where did he go?"

And while Mikey flopped around on the floor with the skill of a fish out of water, and Don berated the device on his wrist, Leo stepped backwards until he was out of sight from the two.

The second youngest smiled, his eyes focused on the lair door that was _ajar._

Leo smirked, "Aww. Raph left it open for me!"

But Leo _knew_ that Raph was in the kitchen. Shell, he could even _smell_ the sneak stink. And it struck him as odd, as to how he could tell just what his largest brother was up to by mere scent. If Leo really wanted, he could have asked Don to explain just how that was possible. But Leo didn't really want that. What the turtle _really_ wanted, was to sneak outside the lair just for _one_ _teensy tiny moment._

The turtle cast a quick glance over his shoulder to find Don kneeling beside a wiggling creature they all knew as Mikey. Leo nodded to himself, and snuck yet another look at Raph.

Was he… eating _more salami_?

Leo shuddered, and forced all thoughts of the disgraceful Raphael out of his mind.

Now that Leo determined the lair to be safe enough to disappear for a moment, he took a few cautious steps. Then he announced just above his usual tone, "Raph? Are you outside?"

Leo wrinkled his nose, Raph's guilt stink was beginning to smell really pungent these days. But Raph wouldn't answer- he wouldn't want to be caught stealing more food from the kitchen. Raph _daren't_ answer. And that Leo was what counting on.

Leo took a large step so that he was directly in front of the lair, and he raised his voice just a little louder, " _Oh Raphie!_ You out there?"

Raph peeked from the kitchen door, eyes wide as he whispered, "Leo! No!"

Leo pretended not to hear him, and the turtle put his hands on his hips, "Hmm. I better go check outside for Raph."

He pushed open the door, and threw his voice so Raph could hear everything, "I'll come right back if I don't find him soon."

A lie. That Raph fully believed.

And Leo could almost hear the wheels in his head turning, and just as the turtle stepped out of the lair, he heard Raph sigh in acceptance.

The blue turtle fist-pumped the air, and gave a low shout of pure joy when he heard no yelling of his name. He dashed forward, heading straight down the dirty sewers to a specific manhole cover.

The turtle didn't resist his giggles when he realized that he had- once again, thwarted Raph into believing another trick. Of course Raph would let him go- because Raph honestly believed that Leo would try to find him outside, then give up after the next ten minutes- twenty if Raph thought Leo was feeling extra hopeful, and then Leo would return home.

Leo shook his head, "Raphie boy, you trust me too much,"

And Leo liked it just the way it was. The less they suspected him, the easier his mischief could be. And what mischief it was.


	2. A Surprise

_Here's the mischief Leo found himself in. A bit familiar to us more than him, hope you enjoy this one! Cause we might glimpse Casey. (oops, spoilers)_

* * *

Leo turned a sharp right, his feet nimbly dodging the debris that threatened to pull him down. The sewers reeked with all sorts of unthinkable horrors, but thanks to Donnie's life-saving tech, the turtles could drink this filthy water and survive. Not that Leo was ever going to get that desperate. But Raph might.

Leo shuddered, nearly stopping in his quick jog. Raph truly was a unique turtle, and it near-worried Leo to know that once Raph was in a fitting situation, he would eat everything and anything.

Such is the reason April put a lock on her fridge.

Okay- maybe Leo was the reason April put the lock on her fridge. Leo and his portal. But some things are better left unsaid.

Leo took a sharp left, followed by a couple random but planned twists. The sewer waters were beginning to thin out now, and the liquid faded into near crystal clear. Less trash. Less city filth.

The turtle stopped under a manhole cover, and opted to lean on the ladder to catch his breath, "Besides, I've got at least a half an hour topside before the guys come out looking,"

Leo swung himself up to the middle rung, his feet nearly slipping in the slick but his hands holding him in place. He frowned, and gripped tighter in case he fell.

The turtle rolled his eyes, "Wouldn't want me falling to my death,"

Up he went. To the top. Where the manhole cover was the only thing separating him from the sweet fresh air of freedom.

Leo grinned, and pushed with one hand. The cover slid off easily, and with a skill that came from secret practice, Leo leaped out and replaced the cover in one fluid motion.

All was quiet. No noise. No distractions. It was…

Leo breathed out low, "Peace…"

The turtle sighed, and let his body droop forward. His eyes drifted shut, and for a moment, he felt absolute relaxed. Nothing to concern him.

Leo, ever so slowly, savoring this, inhaled some beautiful fresh air.

No smoke. No distant smell of trash. No drifting stale urine.

 _While his up-beat family was fun, there were times... Rare times... Leo, the guy with the quick wit and awesome one-liners... liked to bask in the quiet._

 _A thing he never wanted to be revealed..._

 _His brothers were sure to point fingers and laugh- because Don was supposed to be the soft-shelled one. Not Leo._

 _So he daren't tell them anything but what they wanted to hear._

 _They wanted a fun-loving, pun-spewing, action-loving brother. This quiet... somewhat sensible, over-thinking turtle was one that Leo wanted to oh-so-desperately push away and never come out. It would never fit in with the dynamics of his laid-back family..._

The world of the sewer and the city was a lifetime away. And for a moment… just one moment… Leo found himself the oh-so-sacred calm.

Leo exhaled, long and low, just because he could. The wind tickled his skin every now and then, but it was nothing like the harsh slap of some whizzing car, no… this breeze was a gentle caress across his face, picking up his mask tails and fondling it gently.

A bit chilling, but never harsh. Leo shuddered, but moved little. The wind was persistent now, trailing across his head, touching his neck in an almost loving manner. And then… it hovered at the bottom of his mask.

Leo's breath hitched, the feeling of cold somehow getting warmer as it _oh-so-delicately_ fingered the red on his face. Leo bit his lips, and he could distinctively feel his mark being traced… almost curiously… And…

And normally he detested whenever his marks were touched. They were his sacred curse, and he loathed whenever his brothers went near enough to purposely poke at him. Or _shell-he-hated-when-they-did-this_ … when they openly teased him about being different. Sure it's all fun and games, but sometimes, the jeers hit somewhere closer than what Leo liked to believe in.

But this?

This wonderful, wonderful, almost too good to be true… gentleness?

 _It felt nice…_

And Leo's cheek was being cupped, so softly. Nothing like what he was used to. Not Raph's playful (albeit hurtful) punches, not Mikey squeezing his face to talk to him, not Don grabbing him to keep him still, not Splinter training him and definitely not April gripping his face to peer into his eyes to decipher some truth or the other.

Leo sighed.

 _This… he could get used to…_

Leo tilted his head, and allowed his cheek to rest there for a while. The touch lingered, and he let out a content little sigh at how wonderful everything was feeling.

And something sighed back.

Leo's eyes shot open in a face full of pure panic, "Huh?"

Leo pitched backwards and onto the ground, "GAH!"

And Leo's scream was immediately cut short when he found that whatever had been there touching him was also screaming too. Leo's mouth clamped shut with an audible click, and for some reason, so did his companion.

Leo blinked twice, and rubbed his eyes. The pressure made his eyes water, making his vision all the more blurry. But what Leo could see… He didn't think he wanted to see.

The full moon was out that night, and Leo didn't notice it until it started making all sorts of strange shadows and illuminating things that shouldn't be illuminated.

Leo blinked slowly, watching the figure stiffen and refuse to move. Leo squinted, and found himself recognizing the figure as… human?

The curse slipped out of Leo's mouth, "Aww shell…"

Leo crept backwards but his shell hit the harsh wall, "Who are you?"

The figure winced, and Leo's eyes narrowed, but it barely helped the fact that he couldn't see two feet in front of him. Oh, he hoped that it had two feet. That would make it easier to relate to. Not that he had anything against other mutants, but all Leo wanted to make sure was that whatever it was… wouldn't hurt him… too badly…

 _Why did he leave his swords in the lair?_

That was a foolish mistake to begin with, and now the turtle was paying the consequences.

Leo sat up on one elbow, legs vulnerably stretched out, but his voice cracked, "Um… he… hey?"

The figure shuddered, and knelt low. Leo pulled back his legs just as it reached out. Now would be the perfect time to bolt, but that thing was near his manhole cover. The only other escape would be up on the roofs, but this was an alien part of the city, one that struck him as dangerous, unfamiliar territory.

The moon continued to cast its eerie shine on the thing before him, and Leo found himself shaking as seconds passed in silence. The worst part was, that Leo was _sure_ he was partially hidden by the shadows, so his existence being a mutant turtle could stay concealed for just a while longer.

Leo forced himself to blink slowly again, and his eyes narrowed at the near-glowing figure before him. With vision now clearer, he definitely call the form before him male. Male and… young.

But when Leo leaned a bit forward, he recognized the hair being a bit longer than usual. And the moon wasn't helping one bit, highlighting the subtle muscles on the lean arms, glinting on one black sneaker while the other was caked with mud.

And the face… Leo couldn't see the face. All he could notice, was that those eyes were staring at him. Leo leaned as close as he dared, his knees still clutched to his chest. Maybe if he got close enough, he could find out if it were fully human or…

Leo's jaw dropped, "Red eyes,"

Leo reeled backwards, hugging his knees, "YOU'VE GOT RED EYES!"

The figure jumped, as if never expecting Leo to even say a single word. And a small sound of surprise escaped his mouth just as Leo covered his face in pure reflex. The thing before him gave a yelp and backed away just as Leo ducked under his protective arm...

 _What the shell?_


	3. Insane

_Author's Note:_

 _Third chapter! Still Leo and his inner battle with ditching and staying. Enjoy this chapter,_

* * *

Leo didn't think he believed in ghosts, but cornered by a glowing boy with _freaking red eyes_ made Leo so very sorry he ever doubted Mikey.

 _But there had to be a reasonable explanation!_

 _Until then- Leo was going to take all precautions._

The ghost-thing took a step towards Leo, hands (with five perfectly human fingers as far as Leo could tell) slowly reaching forward. Then retracted.

Leo never took his eyes off it. Although… something told him… maybe… just maybe… it was just as scared as he was.

 _Psh._

 _As if_.

Then the thing spun around, hands on its head and muttering something to the brick wall. Leo arched an eye ridge, tilting his body to peer at it. It sounded very human- but sounds could be deceiving.

The thing slammed its head into its hands, and Leo's eyes near shot to his forehead. Yet… he wasn't as tense as he ought to be.

 _Why?_

The ghost jerked up, and spun around as though just realizing that it was not alone. Leo watched on, never once inching away… nor closer. And he was mildly aware that he had been holding his breath all the while.

And Leo slightly parted his lips, and _slowly_ allowed himself to exhale. But his ghost didn't once notice how his heart had returned to normal, the initial shock wearing off. But curiosity present.

The ghost took a step so small it barely made a difference. And opened its mouth.

And in a voice soft, and not in the least bit unpleasant. A voice that slid out so smoothly, not deep enough to be terrifying, but enough to cause Leo's insides to do a weird little flutter.

 _It wasn't anything like what Leo thought a ghost should sound like._

 _Too nice to be a ghost…_

 _If it even **was** a ghost._

"It's okay turtle thing… I won't hurt you…"

Leo's face fell, and he gave the ghost a half-glare, "Yeah right. As if I'd fall for that!"

Once again, Leo's ghost pulled back, as if the mere sound of Leo had the ability to jerk him right from wherever dream world he had been living in. The ghost shook it's head again, and gave what could be the nicest chuckle Leo ever heard anyone give.

It was just nice enough to have Leo smiling back, and the turtle tilted his head, "You're not going to try to kill me, right?"

Leo held up a hand, "Because I'm warning you…"

Leo's eyes narrowed, "I've got pretty mad fighting skills,"

And at that, Leo's ghost burst into gentle chuckles again. And heaven help Leo, because he found himself willing to do almost any other ridiculous thing in order to hear that sound again.

The ghost shuffled closer to Leo, so that now if Leo wanted, he could touch his ghost's face. And Leo tried to do just that. His three-fingered hand reached up, and he saw his ghost back away. And almost out of habit, Leo pulled back into himself.

Shell, his ghost almost looked _sorry_ to see him do that. But who could blame Leo? In a world where mutants were monsters, trusting became difficult out of survival instincts.

But survival instincts be damned, Leo's ghost was an intricate discovery worthy of Leo's attention and he wanted to know more. _Consequences_ be damned. If he messed up and this was a mistake, it would all be on him, no one else would get hurt, Leo could handle that.

So the turtle relaxed his body, and pulled his most friendly grin, the one with just a slightly smirk behind him, "So… you ghost these places often?"

The ghost didn't answer, it just continued to stare. Leo sighed, and tried again, "You can speak English… right?" Leo's face became thoughtful, "Well you did say _it's okay, and I won't hurt you_ …"

The thing nodded, but otherwise didn't prove anything to Leo. And although Leo would have liked to continue to stare at his discovery, Leo _knew_ that his time was running out. The others would just be wondering where he was.

The turtle slowly put his hands on the ground, and making sure his ghost could see what he was doing, Leo stood. And he offered a hand, "Need a hand… Mr. Ghost Thingy?"

The thing gasped again, and leaned forward. Leo didn't like the fact that he was immediately by its side, showering him with concern he didn't know he had for it.

But after seconds of kneeling beside the trembling figure, Leo recognized a joyous sound. It sounded pure and light… mimicking Mikey's innocence with a hint of Raph's confidence yet not lacking in Donnie's entertainment. But never loud. And Leo recognized the _mischief_ from his own previous chuckles.

But this sound…

It had to be… It was…

Leo pulled back, an eye ridge raised, "Are you laughing?"

His ghost gasped again, clutching his stomach, "You're insane Blue Turtle!"

 _Excuse him?_

 _Leonardo?_

 ** _Insane?_**

 _Of all the…_

Never before had Leo felt so insulted. By a _stranger_ nevertheless! One that he hadn't even known for a full hour yet, was calling _him_ insane. The only thing insane about Leo was his _mad_ skills. Nothing else! He was sane thank you very much.

Leo huffed and folded his arms, "Gee thanks,"

The ghost gasped again, reaching up to… Leo's eyes widened and once again, his face betrayed his pure horror. Leo's ghost stuck his fingers into his chin… and lifted off his face.

Leo's eye twitched, and he was just about to protest and perhaps make a quick getaway when he realized some things.

One: his ghost was still on the ground making those pleasant chimes.

Two: The moon was considerably higher in the air, making everything just a bit more surreal that night.

Three: Leo was now inches away from his manhole cover.

And Four: His ghost was holding a hockey mask.

Leo arched a brow, and frankly, without concern, he grabbed the object, "A hockey mask?"

"Hey!" the hockey mask wearer jumped to his feet, "That's mine!"

One beat, and in a rather playful voice, his ghost told Leo, "Gimme back my mask!"

And Leo was far too smug about the fact that he was a few inches taller than his companion. Wait… Leo's eyes widened, and he glanced down to notice that he was… face to face with a human.

He did what any ninja mutant teenage turtle would do. He bolted into the sewers in record seconds, the manhole cover still shaking when he was at the bottom of the ladder.

Leo dashed in the direction of the lair- the further away from his ghost, the better. It wasn't until Leo was four turns away from his home when he recognized a few very important things.

One: He still hadn't gotten a good look at his ghost... no human… no ghost…

 _It was a ghost until Leo's found more proof!_

Two: He still had the mask in his hands.

Three: He was _way past_ curfew.

Leo bit his lips, and let loose a turtle-themed curse, and he broke into a sprint. But for some reason, he found himself clutching onto his ghost's hockey mask. It felt nice, to know that he had a little secret of his own. Even if it was a little insane.

Leo scoffed, and took a left turn, "Insane…"

"As if!" Leo told a certain chip in the wall.

The turtle slowed his pace, his feet merely wading through the disgusting sewer water. Leo wrinkled his snout, grateful that Don did some science to prevent his footwear from being stained- and thank goodness, from smelling. It was one of Donnie's greatest achievements in their childhood, and perhaps the best… so far…

Who knows what else Don could come up with this time? Leo might not actively show it, but his sarcastic support mostly went in favor of Don's amazing genius. And Leo _knew_ that somehow, Don knew Leo had his back… or shell.

Leo chuckled, and kicked a stray piece of who-knows-what away from his toes. He grinned at it again, and kicked it once more. It was sent shooting to the wall, and bounced right back to the sewers. And before Leo could convince himself otherwise, he went chasing that piece of rubbish down the random tunnel, each kick sending him further and further into the deep disgusting sewers.

Sometimes, it was worth looking over the shoulder in the event of stalkers, but Leo didn't. Why would he? He lived in the sewers. Who was crazy enough to follow him in there? Other than April that is… But these low footsteps, were not April's…


End file.
